Ametek Drexelbrook Impulse GW Series, Installation And Operating Instructions Manual, Page: 71 / 99

Configuration and Calibration
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4.10 Holding and input registers
All data points can be accessed as either a holding or an input register.
Holding registers start with a 3XXXX and Input registers start with a
4XXXX. For example, product can be obtained at both registers 30203
and 40203.
4.11 Maximum registers
The maximum number of registers that can be accessed in a single Modbus
request depends on the mode (RTU or ASCII) and the register size of the
data (i.e Enron uses 4 data bytes per register for floats and longs)
• For ASCII setting , accessing Enron floats or long integers, the maximum
number of registers that can be requested is 30.
• For all other modes, the maximum number is 36, which will retrieve all
the data points in a single message.
4.12 Examples of Accessing Data in the Impulse
For the following examples, suppose we have this value:
Product (level) reading: 200.74 inches.
1) To access product as an integer, Big Endian order:
Request register 31803, length 1, value returned = 20074
2) To access product as an integer, Big Endian, in Enron addressing:
Request register 3002, length 1, value returned = 20074
3) To access Product, level, as a floating point, Big Endian:
Request register 30203, length 2, value returned = 200.74